U.S. patent number 6,761,554 [Application Number 09/888,704] was granted by the patent office on 2004-07-13 for rotary tableting press.
This patent grant is currently assigned to Leraj, Inc.. Invention is credited to Naresh C. Patel.
United States Patent |
6,761,554 |
Patel |
July 13, 2004 |
Rotary tableting press
Abstract
A rotary tableting press includes a turret with upper and lower
carousels in which upper and lower punch assemblies are removably
supported. The upper and lower punch assemblies include punch
casings having a central opening and a punch slidably received in
the central opening of the casing. The upper and lower punches are
normally biased away from one another. Rollers are positioned on
the tablet press and adapted to engage the punches to direct the
upper and lower punches toward one another to compress material
placed between the punches to form a tablet.
Inventors: |
Patel; Naresh C. (East
Brunswick, NJ) |
Assignee: |
Leraj, Inc. (East Brunswick,
NJ)
|
Family
ID: |
25393718 |
Appl.
No.: |
09/888,704 |
Filed: |
June 25, 2001 |
Current U.S.
Class: |
425/345; 425/353;
425/408 |
Current CPC
Class: |
B29C
43/08 (20130101); B29C 43/361 (20130101); B30B
11/08 (20130101); B29C 43/36 (20130101); B29C
43/50 (20130101); B29C 2043/3283 (20130101); B29C
2043/3689 (20130101) |
Current International
Class: |
B29C
43/04 (20060101); B29C 43/36 (20060101); B29C
43/08 (20060101); B30B 11/02 (20060101); B30B
11/08 (20060101); B29C 43/50 (20060101); B29C
43/32 (20060101); B29C 043/08 () |
Field of
Search: |
;425/345,193,352,353,406,408 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Davis; Robert
Assistant Examiner: Nguyen; Thu Khanh T.
Attorney, Agent or Firm: Drinker Biddle & Reath LLP
Claims
What is claimed is:
1. A rotary tableting press comprising: a turret supported for
rotation about an axis, said turret including an upper carousel and
a lower carousel each having a plurality of openings, the openings
in said upper carousel being vertically aligned with associated
openings in said lower carousel; a plurality of upper and lower
punch casings, each of said punch casings having a central opening
and being removably received in one of the openings of said upper
and lower carousels; a plurality of upper and lower punch members,
at least a portion of each of said upper and lower punch members
being slidably received for reciprocation in the central opening of
one of said upper and lower punch casings, each of said upper and
lower punch members including a mold recess at a terminal end
thereof; and means for reciprocating said upper and lower punches
with respect to said upper and lower casings.
2. The rotary tableting press according to claim 1 wherein said
reciprocating means comprises upper and lower rollers supported by
corresponding upper and lower fixed plates, said upper and lower
rollers positioned and oriented to engage a first end of said upper
and lower punch members to direct said upper and lower punch
members toward one another.
3. The rotary tableting press according to claim 2 wherein said
reciprocating means further comprises means for biasing the upper
and lower punch members, said means for biasing upwardly biasing
the upper punch members and downwardly biasing the lower punch
members.
4. The rotary tableting press according to claim 1 wherein the
central opening in each of said lower punch casings includes a bore
extending to a terminal end, and wherein each of said lower punch
casings includes a die portion extending from the terminal end of
said bore to an end of said casing, and an opening defining a
material chamber extending through said die portion and
communicating with said bore, and wherein each of said lower punch
members includes a central body portion slidably received in said
bore and a mold shaft extending from one end of said body portion,
at least a portion of said mold shaft being slidably received in
the material chamber of said die portion, and wherein reciprocation
of each of said lower punch members by said means for reciprocating
results in retraction of at least an end portion of the mold shaft
of said lower punch member from a terminal end of the associated
material chamber, thereby providing for receipt of a tablet
material within the material chamber.
5. The rotary tableting press according to claim 1 wherein the
openings in said upper and lower carousels are arranged in at least
two concentric rows of openings in an outer peripheral portion of
said upper and lower carousels.
6. The rotary tableting press according to claim 4 wherein each of
said upper punch members includes a mold projection extending from
one side of a central body portion, and wherein the mold recess of
said upper punch member is included in the mold projection and
wherein the mold recess of each of said lower punch members in
included in the mold shaft of said lower punch member, the upper
and lower mold recesses positioned such that they are brought into
intimate confronting relationship during said reciprocation of said
punch members, the reciprocation of the punches causing material
between the mold recesses to compress to form a tablet.
7. The rotary tableting press according to claim 6 wherein the
upper and lower mold recesses are substantially similar in size and
shape.
8. The rotary tableting press according to claim 2 wherein each
upper roller includes an arcuate surface which projects below a
lower surface of the upper plate, and wherein each lower roller
includes an arcuate surface which projects above an upper surface
of the lower plate.
9. The rotary tableting press according to claim 2 wherein each of
the upper and lower rollers is fixed against rotation and wherein
the center of each of said upper rollers is in substantial
alignment with the center of one said lower rollers.
10. The rotary tableting press according to claim 6 wherein the
body portion of each upper punch extends above an upper surface of
the upper punch casing, the body portion having an upper end with a
retention flange, wherein the means for biasing includes a first
resilient member contacting the retention flange and the upper
surface of the upper punch casing to bias the upper end of the
upper punch member away from the upper punch casing, and a second
resilient member located between the central body portion of the
lower punch member and the lower punch casing for biasing the
central body portion of the lower punch member away from the lower
punch casing.
11. The rotary tableting press according to claim 10 wherein each
of said second resilient members is a spring located within the
central opening of one of said lower punch casings.
12. The rotary tableting press according to claim 6 wherein the
confronting relationship between the mold recesses in said upper
and lower punch members occurs adjacent to an upper surface of said
lower carousel.
13. The rotary tableting press according to claim 10 further
including a fixed lower plate mounted below the lower carousel, the
lower plate having at least one ejection cam formed on an upper
surface, the ejection cam projecting upwardly from the upper
surface of the lower plate and adapted to contact a follower formed
on and extending downward from the central body portion of the
lower punch member, the contact between the ejection cam and the
follower forcing the mold shaft of the lower punch member to eject
the tablet from the lower punch casing.
14. The rotary tableting press according to claim 13 further
comprising at least one tablet weighting station for metering a
preselected amount of material to be molded in the material chamber
of said lower punch casings, said tablet weighting station
including a doser supported by said tablet weighting station such
that an upper surface of said doser is located adjacent the lower
plate of said tableting press for contact with said follower of
said lower punch members, said tablet weighting station including
an adjustable support for adjustment of the position of the upper
surface of said doser with respect to the lower plate.
15. The rotary tableting press according to claim 8 wherein the
support of at least one of said upper and lower rollers by said
tableting press is adjustable such that the distance which the
arcuate surface projects from the plate may be varied.
16. The rotary tableting press according to claim 3 wherein the
upper end of the upper punch member is rounded and adapted to slide
along the lower surface of the upper plate, and wherein the lower
end of the follower is rounded and adapted to slide along the upper
surface of the lower plate.
17. A rotary tableting press comprising: a turret having upper and
lower portions rotatably supported by said tableting press each
having a plurality of openings such that each of the openings in
said upper portion is aligned with one of the openings in said
lower portion; a plurality of upper and lower punch assemblies each
comprising a punch casing removably received in one of the openings
in said upper and lower turret portions and having a central
opening defining a punch contact surface, each upper and lower
punch assembly further comprising a punch received in the central
opening of said punch casing for sliding contact between said punch
and the punch contact surface of said punch casing, each of said
upper and lower punches including a mold recess at a terminal end
thereof; and means for reciprocating said upper and lower punches
with respect to said upper and lower punch casings.
18. The rotary tableting press according to claim 17 wherein said
reciprocating means comprises upper and lower rollers supported by
said tableting press, said upper and lower rollers positioned and
oriented to engage a first end of said upper and lower punches to
direct said upper and lower punches towards one another, and
wherein said reciprocating means further comprises means for
biasing said upper and lower punches, said means for biasing
upwardly biasing said upper punch members into contact with an
upper plate and downwardly biasing said lower punch members into
contact with a lower plate.
19. A system for supporting punches in a rotary tableting press,
said system comprising: a turret comprising upper and lower
portions rotatably supported by said tableting press, each portion
having a plurality of openings such that each of the openings in
said upper portion is aligned with one of the openings in said
lower portion; a plurality of upper and lower punch casings
removably received in one of the openings in said upper turret
portion and having a central opening defining a punch contact
surface, each upper and lower punch casing receiving a punch for
sliding contact between said punch and the punch contact surface of
said punch casing, each of said punches including a mold recess at
a terminal end thereof; and means for reciprocating said punches
within with respect to said upper and lower punch casings.
20. The system according to claim 19 wherein the central opening in
each of said lower punch casings includes a bore having a terminal
end and wherein each of said punch casings includes a die portion
extending from the terminal end of said bore to an end of said
casing, said die portion having an opening defining a material
chamber extending through said die portion and communicating with
said bore.
Description
FIELD OF THE INVENTION
The present invention relates to a rotary press for manufacturing
tablets and the like.
BACKGROUND OF THE INVENTION
In known presses for manufacturing tablets and the like, granular
material is deposited from a feeder onto the upper surface of a die
table for delivery of the material into die cavities carried by the
die table. Upper and lower punches are positioned in aligned
openings of upper and lower turret parts that are spaced on
opposite sides of the die table. The turret portions and the die
table are secured to a drive shaft for synchronous rotation of the
turret portions and die table by the press. Track guides or cam
structure supported by the press provide for reciprocation of the
upper and lover punches to compress the material that has been
deposited in the die cavities of the die table.
The upper and lower punches of prior art presses reciprocate in
sliding contact directly with openings formed in the turret. This
construction limits the punches that may be used in the press to
those having relevant outer dimensions approximating the opening to
provide for sliding contact between the punches and the turret
portions. Furthermore, the repetitive reciprocation required by the
sliding punches results in wear or other damage to the punches and
to the surfaces of the turret parts that come into contact with the
punches. Because the sliding contact surfaces receiving the punches
are integral to the turret parts, damage to the sliding contact
surfaces represents damage to the entire turret part.
The present invention provides removable punch assemblies for a
rotary press in which the sliding surfaces for the punches are
contained within the punch assembly. The inclusion of the sliding
surfaces within removable punch assemblies provides for variation
in the dimensions of applicable punches thereby leading to a more
universal press. Also, the inclusion of the sliding contact
surfaces within the removable punch assemblies allows different
material to be used for the contact surface of the punch assembly
as compared to the material selected for the turret portion. This
provides for increased control over the portions of the punches and
support structure which come into contact and are subject to wear
or damage. Furthermore, when the sliding surfaces provided for one
of the punches become worn or otherwise damaged, the inclusion of
the sliding surfaces within removable punch assemblies allows for
replacement of an individual punch assembly rather than replacement
of an entire turret portion.
Additionally, conventional presses incorporate a separate die table
located between the punch-carrying turret portions. The die tables
carry the die cavities in which the material to be compressed is
delivered by a feeder. This construction requires that the die
table be secured to the drive shaft of the press or to one or both
of the turret portions such that the die cavities and punches
rotate synchronously.
The removable punch assemblies of the present invention eliminate
the need for a separate die table. The punch assemblies include a
die portion having a material chamber in which the material to be
compressed is delivered. This construction provides for a more
versatile and efficient assembly as compared with conventional
tableting presses.
SUMMARY OF THE INVENTION
According to the present invention there is provided a rotary
tableting press. The tableting press includes a turret rotatably
supported by a housing and having upper and lower carousels. The
upper and lower carousels have aligned openings in which upper and
lower punch assemblies are removably supported. Each of the punch
assemblies includes a punch casing and a punch member slidably
received in an opening of the punch casing. The rotary tablet press
further includes means to reciprocate the punches within the punch
casings.
According to an embodiment of The invention the reciprocating means
includes means for biasing the upper and lower punch members, the
means for biasing upwardly biasing the upper punch members and
downwardly biasing the lower punch members. Rollers supported by
the housing engage the punches to direct the upper and lower
punches toward each other to form a tablet through compression of
material located between the punches.
According to an embodiment of the present invention, the central
opening in each of the lower casings consists of a central bore
having a terminal end and each of the casings includes a removable
die portion extending from the terminal end of the bore to an end
of the casing. The die portion includes an opening defining a
material chamber extending through the die portion.
According to another embodiment of the present invention, each of
the upper and lower punch members includes mold recesses. The mold
recesses are positioned such that the upper and lower mold recesses
are brought into an intimate confronting relationship as, the punch
members engage the cam structure to form a tablet through
compression of material which has been placed between the mold
recesses.
The foregoing and other features and advantages of the present
invention will become more apparent in light of the following
detailed description of the preferred embodiments discussed below
and as illustrated in the accompanying figures. As will be
realized, the invention is capable of modifications in various
respects, all without departing from the invention. Accordingly,
the drawings and the description are to be regarded as illustrative
in nature, and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
For the purpose of illustrating the invention, there is shown in
the drawings a form that is presently preferred; it being
understood, however, that this invention is not limited to the
precise arrangements and instrumentalities shown.
FIG. 1 is a perspective view of a rotary tableting press according
to the present invention;
FIG. 2 is a top plan view of the turret of the rotary tableting
press of FIG. 1;
FIG. 2A is a partial top plan view of a turret having an
alternative arrangement of openings;
FIG. 3 is a sectional view taken along the lines III--III in FIG.
2;
FIG. 4 is an exploded perspective view of an upper punch assembly
of the rotary tablet press of FIG. 1;
FIG. 5 is an exploded perspective view of a lower punch assembly of
the rotary tablet press of FIG. 1;
FIG. 6 is a partial elevational schematic view of the rotary
tableting press of FIG. 1 in which curvature of the tableting press
is removed for clarity to illustrate the press in the plane of the
figure;
FIG. 7 is a schematic illustration of the upper and lower punch
assemblies of the rotary tableting press at various stages of the
tableting process; and
FIG. 8 is an enlarged view taken from FIG. 7.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to the drawings, where like numerals identify like
elements, there is illustrated in FIG. 1 a rotary press 10
according to the present invention for forming tablets and the
like. The rotary tableting press includes a turret 12 that is
supported for rotation in a housing structure 14. The turret 12, as
seen in FIG. 3, has a central opening 16 that provides access for a
drive shaft 20. A motor 18 engages the drive shaft 20 to rotate the
turret 12 about a central axis A--A. The motor 18 is preferably
supported on a base portion 22 of the housing structure 14 beneath
the turret 12.
The turret 12 includes upper and lower carousels, 24 and 26
respectively, (shown in FIG. 3) for supporting tablet molding punch
assemblies which will be described in greater detail below. The
carousels 24, 26 extend annularly around a central disk portion 28
at an outer peripheral portion of the turret 12 and are separated
from one another on opposite sides of channel 30. Each of the upper
and lower carousels 24, 26 includes a plurality of openings 32, 34
which are positioned such that each of the openings 32 in the upper
carousel 24 is vertically aligned with one of the openings 34 in
the lower carousel 26. As best seen in FIG. 2, the openings 32, 34
are arranged in two rows 36, 38 of openings to form concentric
rings of openings such that the position of each of the openings
32, 34 in row 36 is offset from the position of adjacent openings
in row 38. This arrangement of openings provides space saving
efficiency allowing for placement of additional openings, and
therefore additional punch members, in the available space provided
by the carousels for the support of punch members. In FIG. 2A, a
portion of an upper carousel 39 of an alternative production unit
is shown. The alternative production unit provides for additional
openings 32 through the inclusion of four rows of openings 32 in
the upper carousel 39.
The turret 12 is shown in the figures as a unitary construction in
which the outward projecting carousels 32, 34 are integral with the
central disk portion 28. However, it is also contemplated that the
turret may be formed as an assembly having separate upper and lower
plate portions containing the annularly extending carousel portions
which are positioned on opposite sides of a central spacing member
to create a space between the carousels.
Referring again to FIG. 1, the housing structure 14 includes a
tiered assembly 42 that is supported atop the base portion 22. The
tiered assembly 42 includes lower and upper plate members 44, 46
that are spaced from each other by support columns 48 to form a
lower compartment 50. The motor drive shaft 20, shown extending
through the tiered assembly 42, supports the turret 12 for rotation
within the lower compartment 50. As will be described in greater
detail, the lower and upper plate members 44, 46 provide reaction
surfaces for actuated reciprocation of punch members. The tiered
assembly 42 further includes a cover plate 52 supported above upper
plate member 46 by columns 53 to form an upper compartment 54 in
which an upper portion of the motor drive shaft 20 extends.
Referring to FIG. 3, each of the openings 32 in the upper carousel
24 includes a first large diameter portion (or bore) 56 extending
from an upper surface 58 nearly through the thickness of the upper
carousel 24. An opposite terminal end of the large diameter portion
56 defines a supporting surface 60 adjacent a the lower surface 62
of the upper carousel 24. A second smaller diameter portion (i.e.,
hole) 64 of the opening 32 extends from the lower surface 62 to
communicate with the larger diameter portion 56. In a similar
fashion, each of the openings 34 in the lower carousel 26 has a
large diameter portion (or bore) 66 extending from an upper surface
68 of carousel 26 to an opposite terminal end of the larger
diameter portion 66 which defines a support surface 70. A smaller
diameter portion 72 extends from a lower surface 74 of the lower
carousel 26 to communicate with the larger diameter portion 66.
Referring to FIGS. 4-6, as discussed above, the rotary tableting
press 10 includes upper punch assemblies 76 that are removably
inserted into the openings 32 in the upper carousel 24. Each upper
punch assembly 76 includes a casing 78, a punch member 80 and a
spring 82. Each of the upper casings 78 includes first and second
portions 84, 86 and a central opening 88 extending through the
first and second portions to provide an internal channel or contact
surface for sliding and supporting one of the punch members 80 in
casing 78. The first portion 84 of each upper casing 78 has an
outer diameter which is smaller than the outer diameter of the
second portion 86 such that an annular support ledge 90 is formed
by the second portion 86. As shown in FIG. 6, each of the upper
casings 78 is removably received in one of the openings 32 of the
upper carousel 24. The annular ledge 90 is supported on the
supporting surface 60 such that the first portion 84 of the casing
78 extends beyond the lower surface 62 of the upper carousel
24.
Each of the upper punch members 80 includes an elongated body
portion 92 which is slidably received within the central opening 88
of one of the upper casings 78 for sliding contact between the
elongated body portion 92 and central opening 88. Each upper punch
member 80 further includes a mold projection 94 which extends from
an end 96 of the body portion 92 and a stop 98 located at an end
100 of the body portion 92 which is opposite mold projection 94.
Each stop 98 includes an annular surface or retention flange 102
preferably having a diameter (or width dimension) that is larger
than the diameter of the body portion 92 for engaging spring 82.
Each stop 98 further includes preferably a rounded surface 104
opposite the annular surface 102. The preferred rounded surface is
designed to contact the upper plate 46 of housing structure 14 and
other structures associated with the press 10. As such, a rounded
surface minimized friction between the upper punch member 80 and
the housing.
Each of the upper springs 82 is positioned on the body portion 92
of one of the upper punch members 80 and has a first end 106
contacting an upper surface 110 of the punch casing 78 in which the
punch member 80 has been slidably received. An opposite end 108 of
the spring 82 contacts the annular surface 102 of the punch member
80. As a result, the spring 82 biases the punch member 80 upwardly
with respect to the casing 78 and, thus, the upper carousel 24.
The rotary tableting press 10 further includes lower punch
assemblies 112 removably received in the openings 34 in the lower
carousel 26. Similar to the upper punch assemblies 76, each of the
lower punch assemblies 112 includes a casing 114, a punch member
116 and a spring 118. Each of the lower punch casings 114 includes
an elongated central bore 120 which defines a cavity for slidingly
receiving one of the punch members 116 within casing 114. The side
walls of the cavity provide a sliding contact surface for the punch
member 116. The central bore 120 extends from an end 122 of the
casing to a terminal end of the bore that defines a reaction
surface 124 for retaining the spring 118 (see FIG. 7).
Each of the lower punch casings 114 also includes a die portion 125
which extends from the terminal end of the central bore 120 to an
end 130 of the casing 114. An opening or channel 128 extends
through the die portion 125 and communicates with the central bore
120. The channel defines a chamber for receiving material that
forms the tablet.
The inclusion of the sliding surfaces required by the upper and
lower punches 80, 116 within the removable punch assemblies 76, 112
provides for more universal punch selection as well as enhanced
control and maintenance of the punches which are selected for use
with the rotary press 10. Because the sliding surface is provided
within a removable assembly, the diameter of the sliding surface is
not fixed by the size of the openings 32, 34 in the upper and lower
carousels 24, 26. The present invention allows for variation in the
sliding portion of the punches selected for use in the rotary press
10 without the need for further machining or replacement of the
carousels 24, 26.
Furthermore, the inclusion of the contact surfaces in the casings
78, 114 of the removable punch assemblies 76, 112 allows different
material to be used to make the casings than the carousels 24, 26.
As such, it is possible to select material for the casings which
facilitate reciprocation of the punch members, while selecting
material for the carousels that is better designed to support the
anticipated loads. This variation in material properties for the
punch is possible irrespective of the size of punch.
The inclusion of the contact surface for the punches within
removable assemblies 76, 112 further provides for replacement of an
individual assembly having a worn or damaged contact surface rather
than replacement of the entire carousel 24, 26.
Each of the lower punch members 116 includes a cylindrical body
portion 132 which is received in the central bore 120 of one of the
casings 114. Each lower punch member 116 further includes an
elongated mold shaft 134 projecting from an end 136 of the body
portion 132 and which is adapted to be slidably received in the
material chamber 128 of the die portion 125 of punch casing
114.
As is apparent from the figures, the spring 118 is positioned on
the mold shaft 134 such that the spring 118 will be located within
the central bore 120 of the lower punch casing 114. Each of the
springs 118 has a first end 138 contacting the end 136 of the body
portion 132 and a second end 140 contacting the reaction surface
124 of the casing 114. The spring 118 is preferably a compression
spring which acts to downwardly bias the lower punch member 116
with respect to the lower carousel 26 in which the lower punch
assemblies 112 are removably received. Each of the punch members
116 includes an elongated follower 142 extending from an end 144 of
the body portion 132.
Each of the lower punch assemblies 112 is removably inserted into
one of the openings 34 in the lower carousel 26 such that the end
122 of the lower casing 114 is supported on the support surface 70.
The elongated followers 142 of the lower punch assemblies 112
extend from the lower carousel 26 and have rounded ends 146 adapted
to slidingly contact the lower plate 44 of housing structure 14
during operation.
As seen in FIG. 8, each of the mold projections 94 of the upper
punch members 80 includes a mold recess 148 formed in an end 150 of
the mold projection 94 opposite the body portion 92. Similarly,
each of the mold shafts 134 of the lower punch members 116 includes
a mold recess 152 formed in an end 154 of the mold shaft 134
opposite the body portion 132. The mold recesses 148 of the upper
punch members 80 are most preferably similar in size and shape to
the mold recesses 152 of the lower punch members 116. The mold
recesses 148 of the upper punch members 80 cooperate with the mold
recesses 152 of the lower punch members in a confronting
relationship shown in FIG. 8. Compression of material delivered to
the material chamber 128 of casing 114 as the mold recesses
approach each other forms tablets in the manner to be described.
The inclusion of the die portions 125 in the casings 114 of lower
punch assemblies 112 allows for the elimination of a separate die
table. In addition to savings in material costs, this provides for
the elimination in the need for securement of the separate die
table to either the drive shaft 20 or the turret 12 of the rotary
press 10.
As described previously, the construction of the upper and lower
punch assemblies 76, 112 provides for upward biasing of the upper
punch members 80. The biasing results in contact between the stops
98 and upper plate 46 of housing structure 14 and for downward
biasing of lower punch members 116 for contact between the
elongated follower 142 and lower plate 44 of housing structure 14.
The rounded surfaces 104, 146 of the stop 98 and follower 142
facilitate sliding contact between the punch members 80, 116 and
plates 46, 44 respectively, as the turret 12 is rotated by drive
motor 18.
Referring now to FIG. 6, the rotary tableting press 10 also
includes upper and lower roller assemblies 156 mounted to the
plates 44 and 46 of housing structure 14. The roller assemblies 156
produce the reciprocating actuation of the upper and lower punch
members 80, 116 within the upper and lower carousels 24, 26
respectively. The press preferably includes two upper roller
assemblies mounted on opposite sides of the upper plate 46. Each
upper roller assembly includes an upper roller housing 158 mounted
to the upper plate 46. An upper roller 160 is mounted within the
housing 158 at a central axis of the roller such that a peripheral
portion 164 of the roller 160 extends past the lower surface 166 of
upper plate 46. It is preferable that the roller be fixed against
rotation about the central axis. However, fixation of roller is not
a requirement. The lower projecting portion 164 of the roller 160
thus forms a cam surface which is located to come into contact with
the stops 98 of each of the upper punch members 80 as the turret 12
is rotated.
As the stop 98 of a punch member 80 engages the arcuate peripheral
projecting portion 164 of the roller 160, the punch member is first
driven downwardly until the punch member reaches the center 162
(apex) of the roller 160. After passage of the punch member 80
beyond the center 162, resilient action of the spring 82 which
engages the annular surface 102 of the punch member 80 urges the
punch member upwardly into contact with the surface 166 of upper
plate 46.
There are also preferably two lower roller assemblies 156 mounted
on opposite sides of the lower plate 44 on the rotary tableting
press 10. Each lower roller assembly includes a lower roller
housing 168 and a roller 170 mounted at a center 172 to the roller
housing 168 such that a peripheral portion 174 of the lower roller
170 projects upward beyond the upper surface 176 of lower plate 44.
Similar to the upper rollers 160, it is preferable although not
required that the lower rollers 170 be fixed against rotation.
Accordingly, as the followers 142 of the lower punch assemblies 112
slide along the upper surface 176 of the lower plate 44 they come
into contact with the lower roller 170. The projecting portion of
the roller urges the lower punch member upward, compressing the
spring 118 and driving the lower mold recess upward toward the
upper mold recess 148. When the follower passes the apex of the
lower roller 170, the spring 118 biases the lower punch member 116
downward and away from the lower carousel.
The preferred embodiments of the various figures show the use of
springs 82 for upwardly biasing the upper punch members 80 and
springs 118 for downwardly biasing the lower punch members 116.
However, the invention is not limited to the use of springs. Any
means for biasing the punch members 80 and 116, including pneumatic
and hydraulic actuation for example, has potential application to
the present invention.
As seen in FIG. 6, the centers 162 of upper rollers 160 are
substantially aligned with the centers 172 of the lower rollers
170. As the punch members 80, 116 are driven toward the centers,
the mold recesses 148, 152 of the upper and lower punch members 80,
116 are driven toward one another as shown in FIG. 8. To allow for
adjusting of the mating of the mold recesses, the lower rollers 170
are mounted to an adjustment mechanism 178 which permits vertical
adjustment of the amount that the lower rollers 170 project above
the upper surface 176 of lower plate 44.
The rotary tableting press 10 further includes one or more tablet
weighting stations 180 supported by the lower plate 44 of the
housing structure 14. The weighting stations control the measuring
of a predetermined amount of material 181 into the material
chambers 128 of lower punch casings 114. A conventional material
dispenser, not shown, precedes the tablet weighting stations 180
and deposits material onto the upper surface 68 of lower carousel
26 such that the material 181 enters into, and overfills, the
material chambers 128 beyond the surface 182 of casing 114. See
FIG. 7A. The tablet weighting station 181 includes a doser 183
having an upper surface 184. As a lower punch assembly 112, which
has been filled with material 181 by a dispenser, enters the tablet
weighting station 180, the follower 142 of the lower punch member
116 contacts the upper surface 184 of the doser 183. The upper
surface 184 of doser 183 positions the punch member 116 at a
predetermined position with respect to the material chamber 128 of
punch casing 114. A conventional scraper, not shown, removes excess
material from surface 182 of casing 114 resulting in the
arrangement shown in FIG. 7B.
The tablet weighting station 180 also includes an adjustment
mechanism 186 for adjusting the position of the doser 183 with
respect to the upper surface 176 of lower plate 44. Each of the
tablet weighting stations 180 includes a wedge 188 for maintaining
the position of the doser set by the adjustment mechanism 186. The
punches containing metered material engage the upper and lower
rollers 160, 170 to bring the mold recesses into the confronting
relationship to compress the material as shown in FIG. 7C and FIG.
8.
The rotary tableting press 10 further includes ejection cams 190,
each of which extends upwardly from surface 176 of lower plate 44.
The ejections cams 190 are positioned to contact the followers 142
of lower punch members 116 after the punch members have been driven
past one of the pairs of upper and lower rollers 160, 170. Each of
the ejection cams 190 includes ramped portions 192 and 194. Ramped
portion 192 provides for extension of a lower punch member 116
beyond surface 182 of casing 114 to eject a molded tablet 196 from
the lower punch casing 114 as shown in FIG. 7D. Ramped portion 194
provides for the return of the follower 142 of lower punch 116 and
contact with the surface 176 of plate 44 as shown in FIG. 7E.
While the present invention has been described in connection with
the preferred embodiments of the various figures, it is to be
understood that other similar embodiments may be used or
modifications and additions may be made to the described embodiment
for performing the same function of the present invention without
deviating therefrom. Therefore, the present invention should not be
limited to any single embodiment, but rather should be construed in
breadth and scope in accordance with the recitation of the appended
claims.
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